This invention relates to devices for manually placing or implanting bone anchor screws into bone and to methods of using these devices.
In elderly women, the bladder and proximal urethra tend to descend from their normal anatomic positions such that the bladder neck and proximal urethra move away from the posterior wall of the pubic bone, producing a condition known as stress urinary incontinence (SUI). This condition may be treated surgically, using sutures to fasten periurethral tissue to the pubic bone as a means of repositioning and resuspending the bladder and proximal urethra. The sutures are anchored to the pubic bone using bone anchor screws.
Bone anchor placement devices, such as bone anchor drivers, may be used to place a bone anchor screw at a selected insertion site in the bone. Either percutaneous or transvaginal surgical procedures may be performed using such devices. Percutaneous procedures require an incision in the abdominal wall and/or anterior vaginal wall in order to introduce the bone anchor placement device and are necessarily invasive and traumatic to the patient. Transvaginal such procedures are cost-limiting and may not be readily available when required to perform surgery. Typical bone anchor placement devices used in transvaginal procedures are configured like power drills and are cannulated.
A suture may be threaded into a bone anchor screw prior to, or after, its insertion into the pubic bone. Load on a suture at the point of attachment of the suture to the bone anchor screw can cause breakage of the suture requiring additional, undesired surgery.
The present invention relates to manual bone anchor placement devices. The manual bone anchor placement devices disclosed herein are particularly useful in transvaginal methods of treating female urinary incontinence, although they can be used in other medical applications. The devices of the present invention are designed to permit rotational insertion of a bone anchor screw and to provide low cost alternatives to powered cannulated drills. The devices may be disposable or may be modular in nature, thereby allowing interchange of parts for reuse.
An advantage of the disclosed manual bone anchor placement devices is that they eliminate the need for a percutaneous incision to access an insertion area, although the devices can be used in a percutaneous procedure. A transvaginal approach to inserting a bone anchor screw into the pubic bone is far less invasive than a percutaneous procedure, thus a transvaginal procedure is far less traumatic for the patient.
An additional advantage of the disclosed manual bone anchor placement devices is that they seat a self-tapping bone anchor screw with a pre-attached suture. Since the bone anchor screw used with the disclosed devices is self-tapping and the suture is pre-attached, it is unnecessary for the physician to prebore a hole into the bone, remove the drill, introduce a seating device, seat the bone anchor screw, and then thread the suture. Single-step insertion of the bone anchor screw and suture not only reduces the total time required for the procedure, it also greatly reduces the possibility that the physician may lose access to the bored hole or seated bone anchor screw. Thus, the possible need to drill additional holes and/or seat additional bone anchor screws is reduced.
The manual bone anchor placement devices disclosed herein provide a mechanism to translate linear force exerted by a user on a lever into rotary force on a bone anchor screw. In one aspect of the invention, the manual bone anchor placement device comprises a manually-actuatable lever, a resilient element, a force translator, and a rotator. The force translator is coupled at its distal end to the lever and at its proximal end to the resilient element. The resilient element is coupled to the rotator. Linear force on the lever is transmitted through the force translator to the resilient element and from the resilient element to the rotator. The rotator rotates in response to this force. The device may further comprise a securing element coupled to the rotator which mates with a bone anchor screw and rotates when the rotator rotates, thereby applying a torque on the bone anchor screw, placing the bone anchor screw into bone.
In another aspect of the invention, the manual bone anchor placement device comprises a manually-actuatable lever, a force translator, a rack, and a rotator. The force translator comprises a distal end and a proximal end, the distal end receiving force from the lever, the proximal end being coupled to the rack. The force translator transmits force to the rack which moves linearly into an engaging position in response to this force. The rotator is positioned in close proximity to the rack for engagement with the rack when the rack moves into the engaging position. Engagement of the rotator by the rack causes the rotator to rotate. The device may further comprise a coupler coupled to the rotator which mates with a bone anchor screw and rotates when the rotator rotates, placing the bone anchor screw into bone.
In another aspect of the invention, a manual bone anchor placement device is disclosed which comprises a manually-actuatable lever, a driver rod comprising threads, and a cup and washer positioned over the threads. The cup is coupled to the lever and moves axially along the driver rod upon actuation of the lever, engaging with the washer. When the cup and washer engage each other, linear force transmitted from the lever through the cup is translated to a rotary force on the driver rod, rotating the driver rod. The device may further comprise a coupling element for mating with a bone anchor screw, and for rotating when the driver rod rotates to place the bone anchor screw into bone.
The present invention also relates to a self-tapping buttress-shaped bone anchor screw. The bone anchor screw of the present invention comprises a micropolished eyelet for receiving a suture. The eyelet may be circular, ellipsoidal, or tear-drop shaped. The bone anchor screw described herein is designed to require less torque to seat and to minimize load on a pre-attached suture in comparison with known bone anchor screws.
Kits are also disclosed comprising any of: a molded flexible sleeve for enclosing a suture, a retaining clip for preventing the suture from slipping out of the sleeve, a buttress-shaped bone anchor screw comprising a micropolished eyelet for receiving a suture, and a suture which may, or may not, be pre-attached to the bone anchor screw. A collapsible, protective cover for a bone anchor screw is also disclosed.
The foregoing and other objects, aspects, features, and advantages of the invention will become more apparent from the following description and from the claims.